wc -l metals.txt
grep -E '中国(,|$)|中国香港|中国台北' metals.txt | sort -t',' -k5 -nr
sort -t',' -k4nr metals.txt | head -n5 | cut -d',' -f1
sort -t',' -k2nr metals.txt | head -n5 | cut -d',' -f2 | awk '{sum += $1} END {print "金牌总数：", sum}'
